The AMPIX electrochemical cell: a versatile apparatus forin situX-ray scattering and spectroscopic measurements (original) (raw)
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X-Ray Absorption Spectroscopy Study of Battery Materials
X-ray Characterization of Nanostructured Energy Materials by Synchrotron Radiation, 2017
X-ray absorption spectroscopy (XAS) as a local structural tool for the study of the electrochemical processes in battery materials is highlighted. Due to its elemental specificity and high penetration of the X-rays in the 4-35 keV range, XAS is particularly suited for this, allowing the study of battery materials using specifically developed in situ electrochemical cells. This energy is required to dislodge one core electron from transition metal or p-group atoms, which are commonly used as redox centers in positive and negative electrode materials. In such a simple picture, the ejected photoelectron is scattered by the surrounding atoms, producing characteristic traces in the X-ray absorption spectrum. Both positive and negative electrode materials (intercalation, alloy and conversion electrodes) can be studied. The chapter starts with an introduction of the context around battery studies, followed by a short explanation of the photoelectric effect at the basis of the X-ray absorption phenomenon and to specific features of XAS. A selection of XAS experiments conducted in the field of batteries will be then outlined, also emphasizing the effects due to nanoscale dimension of the material studied. Finally, a perspectives section will summarize the specific role that this spectroscopy has played in the battery community.
Chemical reviews, 2017
Rechargeable battery technologies have ignited major breakthroughs in contemporary society, including but not limited to revolutions in transportation, electronics, and grid energy storage. The remarkable development of rechargeable batteries is largely attributed to in-depth efforts to improve battery electrode and electrolyte materials. There are, however, still intimidating challenges of lower cost, longer cycle and calendar life, higher energy density, and better safety for large scale energy storage and vehicular applications. Further progress with rechargeable batteries may require new chemistries (lithium ion batteries and beyond) and better understanding of materials electrochemistry in the various battery technologies. In the past decade, advancement of battery materials has been complemented by new analytical techniques that are capable of probing battery chemistries at various length and time scales. Synchrotron X-ray techniques stand out as one of the most effective meth...
Solid State Ionics, 2005
An electrochemical in-situ cell for diffraction studies of battery materials has been developed. The cell works in transmission geometry with sample rotation, and the performance was characterized by experiments on the cathode material LiMn 2 O 4 . Several charge and discharge cycles can be studied over a few days without any misfunction of the cell. The quality of the obtained data allows for full structure refinements by the Rietveld method. The whole set-up is about 1 mm thin and consists of an aluminum piston as cathode current collector with a thickness below 0.1 mm in direct contact with a pellet of active cathode material, carbon black and binder. The lithium anode is separated from the cathode by a glass-fibre, soaked with electrolyte. The very good time and angular resolution of this set-up reveals three distinct spinel phases for different charging states of LiMn 2 O 4 , prepared by subsolidus reaction. D
Applied Physics Letters, 1996
Hard x rays from a synchrotron source were utilized in diffraction experiments which probed the bulk of electrode materials while they were operating in situ in battery cells. Two technologically relevant electrode materials were examined; an AB 2 -type anode in a nickel-metal-hydride cell and a LiMn 2 O 4 cathode in a Li-ion ''rocking chair'' cell. Structural features such as lattice expansions and contractions, phase transitions, and the formation of multiple phases were easily observed as either hydrogen or lithium was electrochemically intercalated in and out of the electrode materials. The relevance of this technique for future studies of battery electrode materials is discussed.
Journal of Synchrotron Radiation, 2007
An automatic system that allows continuous in situ electrochemical X-ray diffraction measurements has been developed and implemented at the MS-X04SA beamline at the Swiss Light Source. The system consists of an automatic sample changer, improved 'coffee bag' electrochemical cells, and simple control software. The sample changer can sequentially move up to 32 electrochemical cells into the beam. For each cell an independent electrochemical program is possible. The MYTHEN microstrip detector at the beamline enables parallel detection of diffracted X-ray beams and, thus, fast data acquisition, along with a high 2 resolution. In this communication the set-up is presented on two typical examples from the field of lithium-ion batteries, (i) structural changes in a layered LiCoO 2 positive electrode upon battery charging and (ii) the effect of co-intercalation of ionic liquids into the graphite negative electrode.
Nature Communications, 2013
Developing high-performance batteries relies on material breakthroughs. During the past few years, various in situ characterization tools have been developed and have become indispensible in studying and the eventual optimization of battery materials. However, soft X-ray spectroscopy, one of the most sensitive probes of electronic states, has been mainly limited to ex situ experiments for battery research. Here we achieve in situ and operando soft X-ray absorption spectroscopy of lithium-ion battery cathodes. Taking advantage of the elemental, chemical and surface sensitivities of soft X-rays, we discover distinct lithium-ion and electron dynamics in Li(Co 1/3 Ni 1/3 Mn 1/3 )O 2 and LiFePO 4 cathodes in polymer electrolytes. The contrast between the two systems and the relaxation effect in LiFePO 4 is attributed to a phase transformation mechanism, and the mesoscale morphology and charge conductivity of the electrodes. These discoveries demonstrate feasibility and power of in situ soft X-ray spectroscopy for studying integrated and dynamic effects in batteries.
In situ X-ray absorption spectroscopy—A probe of cathode materials for Li-ion cells
Fluid Phase Equilibria, 2006
In situ X-ray absorption spectroscopy is a powerful emerging technique that has the capability to observe the changes in ongoing electrochemical reactions. It is already well established in materials science, and it is becoming a significant tool for the electrochemical community. As with all X-ray absorption spectroscopies, extended X-ray absorption fine structure (EXAFS) has the advantage of being element specific. Interpretation of the spectra at different states of charge can provide very useful quantitative and qualitative information about the valence change of the constituent elements in the cathode material during the ongoing electrochemical reaction, the degree of distortion or changes in structure from the initial state of charge to the final state of charge and provide valuable information about the extent of degradation of the cathode material during continuous cycling. It can also provide valuable insight about how the nature of the electrochemical reactions changes when one of the transition metal constituents is removed or increased in content in the cathode material. It is often important to adjust the composition of the cathode material in order to achieve high specific capacity and long-term stability in Li-ion cells. This article details the development of the in situ XAS techniques to study electrochemical reactions using various X-ray absorption spectroscopies which are now possible with the advent of third generation synchrotron radiation sources and improved end stations. The strength of in situ EXAFS techniques is illustrated using examples of various interesting transition metal oxides. In this way, we aim to encourage chemists, chemical engineers and materials scientists to consider in situ X-ray absorption spectroscopy as an effective tool for developing an understanding the electronic structure of materials and the changes that it undergoes during electrochemical reactions. (A. Deb).
Electrochemical in situ reaction cell for X-ray scattering, diffraction and spectroscopy
We present a spectro-electrochemical in situ cell for hard X-ray experiments. The cell contains beryllium X-ray windows and allows for scattering and absorption experiments in the transmission geometry. Sealing with three concentric O-rings proofs sufficient for long-term battery cycling. The cell was tested with LiMn2O4 electrodes. Preliminary X-ray absorption and scattering data are shown as well.
Energies
The main challenges facing rechargeable batteries today are: (1) increasing the electrode capacity; (2) prolonging the cycle life; (3) enhancing the rate performance and (4) insuring their safety. Significant efforts have been devoted to improve the present electrode materials as well as to develop and design new high performance electrodes. All of the efforts are based on the understanding of the materials, their working mechanisms, the impact of the structure and reaction mechanism on electrochemical performance. Various operando/in-situ methods are applied in studying rechargeable batteries to gain a better understanding of the crystal structure of the electrode materials and their behaviors during charge-discharge under various conditions. In the present review, we focus on applying operando X-ray techniques to investigate electrode materials, including the working mechanisms of different structured materials, the effect of size, cycling rate and temperature on the reaction mech...